With regard to a method for the synthesis of alkenylphosphine oxides, there have been known a method where an organic metal reagent such as an alkenyl Grignard reagent is made to react with a phosphorus halide compound, a method where secondary phosphine oxide is made to react with an alkenyl halogen compound, etc. However, in the former method, there is a disadvantage that it is accompanied with production of salt of magnesium, etc. while, in the latter method, it is necessary that a base is added so as to trap the generated hydrogen halide as a salt. In addition, both of those methods are not preferred from an industrial view in such a respect that other compounds besides the desired compound are also formed as by-product.
In the meanwhile, it has been recently found a method where a secondary phosphine oxide added to an acetylene compound in the presence of a palladium catalyst (Orgnometallics, volume 15, page 3259, 1996; Japanese Patent No. 2,849,712) but selectively of the product is not high in this method.
With regard to a method for the synthesis of alkenylphosphinic acid esters through carbon-phosphorus bond forming reaction, the most general method is a substitution reaction of the corresponding alkenyl halide compound with a hydrogen phosphinic acid ester. However, in this method, it is necessary to add a base for trapping of hydrogen halide which is produced simultaneously as a result of the reaction whereby large quantities of hydrogen halide salt are produced at the same time. In addition, the alkenyl halide compound which is a starting material therefor is not always easily available industrially and, further, it usually has toxicity. Therefore, the method is never a method which is industrially advantageous.